1. Field of the Invention
This invention relates to separator discs for separating two or more materials in a tubular member, and more specifically, to an improved separator disc for separating materials in tubular members, as, for example, multicompartment tubular hypodermic syringes, and a method of operating the same.
2. Discussion of the Prior Art
Devices exist in the prior art in which tubular members contain separated different materials which are admixed prior to use. Separation of the materials is accomplished by a disc positioned transversely of a tubular member, which disc usually seals along the interior wall of the tubular member until such time as it is desired to intermix the two or more materials separated by the discs. Typical such devices are hypodermic syringes including at least one tubular barrel in which a disc is positioned in the barrel to separate components on each side of the disc.
There are numerous examples in prior patents of plural compartment members used to separate material by a disc. U.S. Pat. No. 2,610,628 of Sept. 16, 1972 describes a disc in the form of a gate plug held in place by seats, the diameter of the plug being less than the normal diameter of the tubular bore. U.S. Pat. No. 3,410,444 of Nov. 12, 1968 describes a container in which two hollow members are separated by a sleeve and plug arrangement. As the two members are moved axially towards each other, the plugs are unseated. U.S. Pat. No. 3,494,539 of Feb. 10, 1970 describes a two-compartment syringe in which a separator disc positioned transversely of the barrel is seated on a support member. Movement of the plunger causes the disc to tilt, thus forming a passageway between the chambers. U.S. Pat. No. 3,699,961 of Oct. 24, 1972 describes various forms of hypodermic syringes in which the plunger of the syringe is used to form two separate compartments. U.S. Pat. No. 3,908,225 of May 7, 1974 describes a container having two compartments separated by a disc. The disc is forced into a compartment of a larger diameter in order to effect mixing of the materials in the compartments. U.S. Pat. No. 3,842,836 of Oct. 22, 1974 is somewhat similar to the structure of U.S. Pat. No. 3,809,225. U.S. Pat. No. 4,113,098 of Sept. 12, 1978 describes a two-chamber ampule.
U.S. Pat. No. 3,494,359 discloses a structure in which two chambers are formed in a tubular barrel by a separator disc which rests on a support on the inside surface of the tubular barrel. The support functions as a cam for the separator to cock the separator out of a transverse orientation. In operation, a plunger must pass over the support on the inner side wall of the barrrel which forms the cam for the separator. For the plunger to accomplish its purpose, the plunger edge must have a close physical relationship to the inner wall of the barrel to form a seal. Thus, as the plunger comes into contact with the support on the inner side wall which forms the cam for the separator, an interference fit occurs which necessitates additional pressure and force on the plunger to overcome. When the syringe is being used in a pharmaceutical application for injection of materials into either human beings or animals by needle, the extra pressure and force which is instantaneously needed to overcome the interference of the support on the inner side wall of the barrel causes the entire syringe to deviate from its vertical and transverse orientation with respect to the subject being injected and thus may cause excess pain to be induced in the subject and may cause the materials being injected to be expressed in an area deeper within the subject than the user of the syringe had contemplated. At best, this may constitute a painful nuisance and at worst, the problem may constitute a dangerous set of circumstances with respect to the health and well-being of the subject being injected. In a nonpharmaceutical application of the syringe, the deviation in position of the syringe as the plunger is depressed may cause the materials being expressed out of the syringe to be applied other than where the user intends that the materials be applied.
As is apparent from the above discussion, the bulk of the prior devices use either seats on the bore of the panel to provide a band of localized reduced cross section as compared to the normal bore diameter, or involve separate chambers of different cross section. In these latter structures, the disc is positioned transversely of the bore having the smaller cross section and intermixing of the components involves forcing the disc into the chamber having the larger diameter.
In the case of hypodermic syringe, for example, the use of a band of reduced cross section is objectionable because the plunger must move freely and evenly in the bore. Where chambers of different diameters are used, this complicates plunger design since the plunger must seal during passage through the chamber of larger diameter.
It is thus apparent that a need exists for an effective manner of providing a separator disc in tubular members having essentially a uniform diameter along the length, without the necessity of utilizing localized areas of smaller diameter, or internal protrusions on the bore to effect displacement of the disc relative to the bore. Further, the use of bores of uniform diameter vastly simplifies manufacture of such tubular members, especially items such as hypodermic syringes.